400 amp residential service

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VIC1958

Senior Member
Scenario: 400 amp rated meter enclosure with no disconnect. Ground rod GEC bonded to neutral in meter can. Meter feeds two 200 amp panels in house, each panel has a 200 amp disco. Water service GEC is ran to only one of the panels where it lands on the grounding bus. Dosent the other panel also need to be grounded to the water service? Hope this is enough information.
 

suemarkp

Senior Member
Location
Kent, WA
Occupation
Retired Engineer
Is the water pipe a ground electrode, or are you just bonding interior metal piping? You are permitted to ground the system at any point upstream of the panels. So if you are allowed to ground in the meter can, that can ground everything and no GECs would be required to be run to the 200A disconnects. When you start having multiple GECs in different places, it can get confusing as to which grounding scheme should apply. If the water pipe is just a bond, then I think you can run it from either panel without an issue.
 

retire09

Senior Member
The two 200 amp panels would have to be grouped in the same location, each connected to the common grounding electrode system, be service rated and have main breakers.
 

VIC1958

Senior Member
The water service would be a supplemental ground, the water meter is jumped with a bonding jumper so the water pipes are bonded. The two panels are side by side. Each panel is connected to the ground rod via GEC bonded to the neutral in the meter can.
 

retire09

Senior Member
The supply conductors between the meter and the two 200 amp panels are still classified as service conductors and must be installed according to 230.
 

MasterTheNEC

CEO and President of Electrical Code Academy, Inc.
Location
McKinney, Texas
Occupation
CEO
The water service would be a supplemental ground, the water meter is jumped with a bonding jumper so the water pipes are bonded. The two panels are side by side. Each panel is connected to the ground rod via GEC bonded to the neutral in the meter can.

Why would the water service be a supplemental ground?.....if based on the question, the water service obviously qualifies under 250.52(A)(1) based on the OP's statement which was "Water service GEC is ran to only one of the panels where it lands on the grounding bus." the connection to the ground rod would be the supplemental in the equation. The connection of that ground rod can take place at any of the locations depicted in 250.53(D)(2), and it is subject to all items referenced in 250.53(D)(2).

Then your connections options to the separate multiple disconnection means in separate enclosures are shown in 250.64(D)(1) through (3).
 

VIC1958

Senior Member
Why would the water service be a supplemental ground?.....if based on the question, the water service obviously qualifies under 250.52(A)(1) based on the OP's statement which was "Water service GEC is ran to only one of the panels where it lands on the grounding bus." the connection to the ground rod would be the supplemental in the equation. The connection of that ground rod can take place at any of the locations depicted in 250.53(D)(2), and it is subject to all items referenced in 250.53(D)(2).

Then your connections options to the separate multiple disconnection means in separate enclosures are shown in 250.64(D)(1) through (3).

I am confused as to why the ground rod which is bonded to the neutral in the meter can is considered " supplemental" and the street side of the water meter would be considered your "main" point of ground. If I am reading your comments correctly and hopefully I am explaining the situation correctly, you are saying that the ground rod is supplemental because the GEC from the water service lands on the neutral/ground bus in the panel and is considered the main point of grounding. So in the scenario that I first posted, 250.64 (D) comes into play and that both panels need to be connected to GEC from the water service.
 

MasterTheNEC

CEO and President of Electrical Code Academy, Inc.
Location
McKinney, Texas
Occupation
CEO
I am confused as to why the ground rod which is bonded to the neutral in the meter can is considered " supplemental" and the street side of the water meter would be considered your "main" point of ground. If I am reading your comments correctly and hopefully I am explaining the situation correctly, you are saying that the ground rod is supplemental because the GEC from the water service lands on the neutral/ground bus in the panel and is considered the main point of grounding. So in the scenario that I first posted, 250.64 (D) comes into play and that both panels need to be connected to GEC from the water service.
No, what I am saying is that the water pipe ground [assuming it qualified per 250.52(A)(1)] would exist so it would be your electrode. As a result you would need to supplement it in accordance with 250.53(D)(2)...and it can be connected as stated in my original response.

The water pipe ground (if it existed) is your grounding electrode, the additional electrode being added [the ground rod(s)] are to supplement the 250.52(A)(1) Metal Underground Water Pipe electrode....
 

meternerd

Senior Member
Location
Athol, ID
Occupation
retired water & electric utility electrician, meter/relay tech
Is the water pipe a ground electrode, or are you just bonding interior metal piping? You are permitted to ground the system at any point upstream of the panels. So if you are allowed to ground in the meter can, that can ground everything and no GECs would be required to be run to the 200A disconnects. When you start having multiple GECs in different places, it can get confusing as to which grounding scheme should apply. If the water pipe is just a bond, then I think you can run it from either panel without an issue.

Be sure the POCO allows the GEC connection in the sealable meter can. Code allows it but some utilities (like ours) don't. Bonding is fine, but not the GEC. Might save you some rewiring.
 
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